JPH04190889A - Operation method for sewage treating device - Google Patents

Abstract

PURPOSE:To prevent an excessive operation and operate a membrane separating device with a degree of efficiency commensurate with the anticipated amt. of sewage to be treated in order to reduce the cake layer adhering to the membrane surface by varying the intermittent operation time of the membrane separating device in accordance with changes in the water level in a flow-rate. adjusting tank. CONSTITUTION:After being stored in a flow-rate. adjusting tank 1, the liq. 2 to be treated is supplied into an aeration tank 5 in prescribed portions, i.e., a control device 15 causes a liq. supply pump 6 to be driven at the lower limiting value of a second level meter 7 and to be stopped at the upper limiting value thereof. Only when the first level meter 3 indicates the lower limiting or higher value, the liq. supply pump 6 is made operative. In the aeration tank 5, a jet of air is applied from a blower device 9 through an air diffusion pipe 8 to the liq. 2 so as to aerate it and, at the same time, the surface of the separation membrane of a membrane separating device 10 is cleaned with an upward stirring stream produced by the lifting action of air. The membrane separating device 10 is intermittently operated under the negative pressure caused by a suction pump 12 and the liq. separated from the solid is discharged through a treated water discharge pipe 11 to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of operating a sewage treatment apparatus for treating sewage having an irregular inflow rate.

BACKGROUND OF THE INVENTION Conventionally, when treating sewage with an irregular flow rate, the inflowing sewage is once stored in a flow rate regulating tank and then supplied in fixed amounts to an aeration tank. Furthermore, when a submerged membrane separator is used in the aeration tank, the membrane separator is operated intermittently to prevent a cake layer from accumulating on the surface of the separation membrane.

In other words, the membrane surface of the separation membrane in the membrane separator is constantly being cleaned by the upward agitation flow generated by aeration, but by stopping the membrane separator, the cleaning effect increases and the cake layer is reduced due to the relaxation of the separation membrane. Moreover, since the amount of cake layer deposited during intermittent operation is smaller than during continuous operation, it becomes easier to peel off.

In addition, in order to prevent the formation of a cake layer on the membrane surface of the membrane separator, the shorter the operation time in intermittent operation, the more
The longer the pause time is, the better, and the lower the flux (permeation flux through the separation membrane) is set, the better.

Problems to be Solved by the Invention However, in the conventional configuration described above, intermittent operation of the membrane separation device in the aeration tank is performed regardless of the expected future throughput, that is, the amount of storage in the flow rate adjustment tank. There has been a problem in that excessive operation has to be carried out even though there is ample time to extend the downtime of the equipment.

The present invention solves the above-mentioned problems and relates to a method of operating a sewage treatment apparatus that can efficiently wash a cake layer according to expected future treatment.

Means for Solving the Problems In order to solve the above problems, the present invention provides the following steps: After the water to be treated is once stored in a flow rate adjustment tank, it is supplied at a constant flow rate to an aeration tank.
The membrane separator is operated intermittently to extract treated water while aeration is being carried out in the aeration tank, and the intermittent time between operation and suspension of the membrane separator is changed according to fluctuations in the water level in the flow rate adjustment tank.

In addition, after the water to be treated is temporarily stored in the flow rate adjustment tank, it is supplied at a constant flow rate to the aeration tank, and while aeration is being performed in the aeration tank, the membrane separator is operated intermittently to take out the treated water, and the water level in the flow rate adjustment tank is changed. The structure is such that the flux of the membrane separation device is changed depending on the situation.

Effect: With the above configuration, as the water level in the flow rate regulating tank decreases, that is, as the expected future throughput decreases, the operating time of the membrane separator in intermittent operation is shortened.

At this time, the cycle time of intermittent operation may be kept constant and the operating time may be shortened (and the rest time may be lengthened), or the cycle time itself may be shortened to shorten the operating time and the rest time may be kept constant. .

This prevents excessive operation and allows the membrane separation equipment to operate efficiently according to the expected throughput, reducing the cake layer that adheres to the membrane surface during operation and making it easier to clean the membrane surface with aeration. This will extend the life of the separation membrane of Membrane Separation'SAK.

According to the second configuration, as the water level in the flow rate adjustment tank decreases, that is, as the expected future throughput decreases, the flux of the membrane separation device is reduced, so that the flux that adheres to the membrane surface during operation is reduced. The formation of a cake layer is suppressed, making it easier to clean the membrane surface and extending the life of the separation membrane.

EXAMPLE An example of the present invention will be described below based on the drawings. 1st
In the figure, a flow rate adjustment tank 1 is provided in communication with a water source of water to be treated 2 such as sewage, and a second rubel meter 3 is provided inside the flow rate adjustment tank 1. Further, a water supply pipe 4 is provided near the bottom of the flow rate adjustment tank 1 with one end open and the other end opened inside the aeration tank 5, and a liquid supply pump 6 is interposed in the middle of the water supply pipe 4. ing.

A second level meter 7 is provided inside the aeration tank 5, and a diffuser pipe 8 for aeration is arranged near the bottom so as to communicate with a blower device 9.

Further, above the aeration pipe 8, a membrane separator IO is installed for the water to be treated 2.
A suction pump 12 is interposed in the middle of the treated water take-out pipe 11 which is connected to the permeate flow path side of the membrane separator IO. An electrically operated flow rate regulating valve 13 is interposed therein. Furthermore, stirring blades 14 are arranged below the aeration pipe 8 .

Then, the second level gauge 3, the second level gauge 7, and the liquid feeding pump 6
The suction pump 12 and the flow rate regulating valve 13 are electrically connected to the control device 15.

Hereinafter, the effects of the above configuration will be explained.

The water to be treated 2 is once stored in the flow rate adjustment tank 1 and then supplied to the aeration tank 5 at a constant flow rate. That is, the control device 15 drives the liquid feeding pump 6 at the lower limit value of the second level meter 7, and stops it at the upper limit value. However, the liquid feeding pump 6 can be driven only when the value of the second Lebel meter 3 is equal to or higher than the lower limit value.

In the aeration tank 5, the air supplied by the blower device 9 is blown out from the aeration pipe 8, and the water to be treated 2 is aerated. The membrane surfaces of the 10 separation membranes are cleaned. In addition, the membrane separator IO is connected to the suction pump 12
The solid-liquid separated treated water is taken out to the outside through the treated water take-out pipe 11.

At this time, the control device 15 operates the suction pump 12 intermittently while changing the pattern of the intermittent time between operation and pause of the membrane separation device 10 according to the water level detected by the second level meter 3. For example, as the water level in the flow rate adjustment tank 1 decreases, that is, as the expected future throughput decreases, the operation time of the suction pump 12 in intermittent operation is shortened.

At this time, as shown in Table 1, the cycle time t of intermittent operation is kept constant (10 minutes in this case), the operation time t1 is shortened, and the rest time t2 is lengthened. Also, the second
As shown in the table, the cycle time t itself may be shortened to shorten the operating time t1, and the rest time t2 may be kept constant.

This prevents excessive operation and allows the membrane separator IO to operate efficiently according to the expected throughput, reducing the cake layer that adheres to the membrane surface during operation and cleaning the membrane surface by aeration. Table 1, Table 2, and Table 3 show that the life of the separation membrane of the membrane separation apparatus 10 can be extended.

Then, as the water level in the flow rate regulating tank 1 decreases, that is, as the expected future throughput decreases, the flow rate regulating valve 13 is operated by the control device 15, and as shown in Table 3, the membrane separation device By reducing the flux of No. 10, the formation of a cake layer that adheres to the membrane surface during operation is suppressed, making it easier to clean the membrane surface and extending the life of the separation membrane.

Effects of the Invention As described above, according to the present invention, by changing the time ratio of intermittent operation in accordance with fluctuations in the water level in the flow rate regulating tank, excessive operation is prevented and efficiency is increased according to the expected processing amount. The membrane separation equipment can be operated well, the cake layer that adheres to the membrane surface during operation can be reduced, the membrane surface can be easily cleaned by aeration, and the life of the separation membrane of the membrane separation equipment can be extended. can be achieved.

By reducing the flux in the membrane separation device as the water level changes in the flow rate adjustment tank, the formation of a cake layer that adheres to the membrane surface during operation is suppressed, making cleaning the membrane surface easier and extending the life of the separation membrane. can be achieved.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a sewage treatment apparatus showing one embodiment of the present invention. 1...Flow rate adjustment tank, 2...Water to be treated, 3...Second
Level meter, 5... Aeration tank, 7... Second level meter, I
O... Membrane separation device, 12... Suction pump.

Claims (1)

[Claims] 1. After the water to be treated is stored in a flow rate regulating tank, it is supplied at a constant flow rate to an aeration tank, and while aeration is being performed in the aeration tank, the membrane separator is operated intermittently to take out the treated water, and the flow rate is adjusted. A method for operating a sewage treatment device, comprising changing the intermittent time between operation and suspension of a membrane separation device in accordance with fluctuations in water level in a regulating tank. 2. Once the water to be treated is stored in the flow rate adjustment tank, it is supplied at a constant flow rate to the aeration tank, and while aeration is being performed in the aeration tank, the membrane separator is operated intermittently to take out the treated water, and the water level in the flow rate adjustment tank is changed. A method for operating a sewage treatment device, characterized by changing the flux of a membrane separation device according to.